1. Field of Invention
The present invention relates to interactive processing and presentation of multidimensional data, for example in passive sonar, radar imaging, geophysics, medicine, remote detection, etc.
2. Description of Related Art
The data furnished by a passive sonar is inscribed in a five-dimensional hyper-volume: time, distance, azimuth, frequency, and signal-to-noise ratio.
It is known to present the data to the operator in the form of fixed classical-format images displaying only three volume dimensions per image:
azimuth-time format presenting azimuth scrolling of noisemakers detected by spatial and frequency processing sequences conducted in the xe2x80x9cupstreamxe2x80x9d part of the sonar receiver, with the signal-to-noise ratio being coded by lightness. The operator has no spatial information;
xe2x80x9clofagramxe2x80x9d or xe2x80x9clofarxe2x80x9d format that, in a horizon sector corresponding to a channel formed by spatial processing, presents the frequency information as a function of time with the signal-to-noise ratio being coded by lightness. The operator has no scrolling information to cover the 360xc2x0 of azimuth, or juxtaposes the same number of elementary xe2x80x9clofarxe2x80x9d images as there are channels, requiring a large screen surface with the use of at least two screens, entailing considerable operating difficulties;
xe2x80x9cazimuth-frequency snapshotxe2x80x9d format that presents the frequency information as a function of the azimuth for the present instant or after a fixed temporal integration, with the signal-to-noise ratio being coded by lightness. The operator has no time information.
Complete presentation of the information delivered by sonar thus requires juxtaposition of corresponding elementary three-dimensional images (x, y, and lightness) of cross sections in the data volume, requiring huge display surface areas. The correlation between the various images is not interactive, which is incompatible with the operation need for real-time processing of the sonar data.
Moreover, the sonar images are composed of raw video signals and superimposed synthetic objects (tracks) leading to substantial information flows that have to be controlled in order not to swamp the operator.
The goal of the invention is to improve the performance of current or future passive sonar by interactive data processing, compatible with the real time of the sonar process, and meeting the following needs which are not met by known methods used to date:
ability of the operator to take in all the information supplied by the xe2x80x9cupstreamxe2x80x9d processing sequences, i.e. with a panoramic, multidimensional view, without having to bring up several rigidly predefined images in succession and waiting for them to settle,
dynamic, flexible, and fast correlation between the various pieces of information contained in the cross sections interactively selected in the data xe2x80x9cvolume,xe2x80x9d
creation of interactive filters in the time, frequency, and azimuth dimensions, these filters enabling the information presented to the operator to be confined to the information of interest, without interaction with the xe2x80x9cupstreamxe2x80x9d processing sequences, affording a visual xe2x80x9cprocessing gainxe2x80x9d that improves the efficiency of the Man-Machine system,
compatibility and complementarily between the presentation of so-called synthetic data supplied by the sonar information-processing algorithms and the presentation of the xe2x80x9crawxe2x80x9d data, improved by the invention.
The invention also sets out to create methods calling only on now-classical image-processing and image-manipulation means that are independent of spatial and spectral processing of signals from sonar hydrophonic sensors and that adapt to the parameters of these types of processing such as the number of channels formed, the number of spectral analysis channels, the degree to which this xe2x80x9cupstreamxe2x80x9d processing delivers xe2x80x9crawxe2x80x9d information in the form of time, bearing (or azimuth), frequency, and signal-to-noise ratio quadruplets without preliminary formatting.
The screen surface area involved by using the invention is smaller than that required for classical methods.
Another goal of the invention is to achieve the advantage of completely uncoupling data systems dedicated to xe2x80x9cupstreamxe2x80x9d processing of the sonar receiver, from the graphic data system that carries out processing treatments and supports the Man-Machine interfaces, and to reduce the information flows between these systems: links are only through raw xe2x80x9cquadrupletxe2x80x9d packages and not in formatted images with the redundancies the latter implies.
The invention thus relates to a method for representing a multidimensional data field on a display screen, consisting of using the screen coordinates for two data dimensions and at least two color perception components out of the three components: lightness, hue, and saturation, for at least two other dimensions of said data.
According to other features of the invention:
the method consists of organizing the multidimensional data fields into a volume memory broken down into virtual image planes;
the method consists, in each virtual image plane, of coding specific data sample parameters by graphic parameters, two parameters being related to the memory coordinates and one parameter being coded by pixel dynamics in grey levels;
the method also consists of filtering specific parameters;
the filtering operations are carried out by interactive modifications of transfer tables acting on the grey levels stored in the virtual images;
the filtering operations are conducted by logical and/or mathematical operations between virtual images.
The invention also relates to a method of the type defined above applied to creation of a real image presented on a display screen from results stored im virtual images, characterized in that it consists of ensuring an interactive modification of a final transfer table that calculates the values of the red, green, and blue components of the pixels as a function of the desired lightness, hue, and saturation values.
The invention also relates to a method of creation, from passive sonar data, of operational images controlled interactively by the operator continuously according to operating needs and compatible with the real-time information requirements, characterized by implementing the representation method of the type defined above to create a bearing-time or azimuth-time image, representing frequencies by the hue, and interactive filtering.
According to other features:
interactive filtering involve creation of a hue filter by imaging;
interactive filtering also involves creation of a circulating lofar image interactively adjustable in terms of direction and of bearing range;
interactive filtering also involves creation of an interactively adjustable bearing-time spectral image in the area of interest;
interactive filtering also involves creation of a spectral image in the frequency-bearing format with interactively adjustable history.